Diver's delights

One day a diver was enjoying the aquatic world 20 ft below sea level. He noticed a guy at the same depth he was, but he had on no scuba gear whatsoever.

The diver went below another 20 ft, but the guy joined him a few minutes later. The diver went below 25 ft, but minutes later, the same guy joined him. This confused the diver, so he took out a waterproof chalk-and-board set, and wrote, "How the hell are you able to stay under this deep without equipment?"

The guy took the board and chalk, erased what the diver had written, and wrote, "I'M DROWNING, YOU MORON!!!"